title: The Drosophila homologue of SRF acts as a boosting mechanism to sustain FGF-induced terminal branching in the tracheal system.
abstract: Recent data have demonstrated a crucial role for the transcription factor SRF (serum response factor) downstream of VEGF and FGF signalling during branching morphogenesis. This is the case for sprouting angiogenesis in vertebrates, axonal branching in mammals and terminal branching of the Drosophila tracheal system. However, the specific functions of SRF in these processes remain unclear. Here, we establish the relative contributions of the Drosophila homologues of FGF [Branchless (BNL)] and SRF [Blistered (BS)] in terminal tracheal branching. Conversely to an extended view, we show that BNL triggers terminal branching initiation in a DSRF-independent mechanism and that DSRF transcription induced by BNL signalling is required to maintain terminal branch elongation. Moreover, we report that increased and continuous FGF signalling can trigger tracheal cells to develop full-length terminal branches in the absence of DSRF transcription. Our results indicate that DSRF acts as an amplifying step to sustain the progression of terminal branch elongation even in the wild-type conditions of FGF signalling.
authors.affiliation: Institut de Biologia Molecular de Barcelona-CSIC, Parc Científic de Barcelona, c/ Baldiri Reixac, 10-12, 08028 Barcelona, Spain. louis.gervais@irbbarcelona.org
authors.forename: Louis
authors.initials: L
authors.lastname: Gervais
authors.forename: Jordi
authors.initials: J
authors.lastname: Casanova
mesh_terms: D000818:Animals; D030801:Animals, Genetically Modified; D004330:Drosophila; D029721:Drosophila Proteins / Q000235:genetics / Q000378:metabolism*; D005346:Fibroblast Growth Factors / Q000378:metabolism*; D018507:Gene Expression Regulation, Developmental; D007150:Immunohistochemistry; D038081:Organogenesis / Q000502:physiology; D026362:Serum Response Factor / Q000235:genetics / Q000378:metabolism*; D014132:Trachea / Q000196:embryology* / Q000378:metabolism
chemical_list: D029721:Drosophila Proteins; D026362:Serum Response Factor; C419504:bs protein, Drosophila; D005346:Fibroblast Growth Factors